route {

        # -----------------------------------------------------------------
        # Sanity Check Section
        # -----------------------------------------------------------------
        if (!mf_process_maxfwd_header("10")) {
                sl_send_reply("483", "Too Many Hops");
                break;
        };

        if (msg:len > max_len) {
                sl_send_reply("513", "Message Overflow");
                break;
        };

        # -----------------------------------------------------------------
        # Record Route Section
        # -----------------------------------------------------------------
        if (method!="REGISTER") {
                record_route();
        };


        # -----------------------------------------------------------------
        # Call Tear Down Section
        # -----------------------------------------------------------------
        if (method=="BYE" || method=="CANCEL") {
                unforce_rtp_proxy();
        };

        # -----------------------------------------------------------------
        # Loose Route Section
        # -----------------------------------------------------------------
        if (loose_route()) {

                if (method == "BYE") {
                        if (nat_uac_test("19")) {
                                fix_nated_contact();
                                force_rport();
                        };
                };


                if ((method=="INVITE" || method=="REFER") && !has_totag()) {
                        sl_send_reply("403", "Forbidden");
                        break;
                };

                if (method=="INVITE") {

                        if (!allow_trusted()) {
                                if (!proxy_authorize("","subscriber")) {
                                        proxy_challenge("","0");
                                        break;
                                } else if (!check_from()) {
                                        sl_send_reply("403", "Use From=ID");
                                        break;
                                };
                                consume_credentials();
                        };

                        if (nat_uac_test("19")) {
                                setflag(6);
                                force_rport();
                                fix_nated_contact();
                        };
                        force_rtp_proxy("l");

                };

                route(1);
                break;
        };

        # -----------------------------------------------------------------
        # Call Type Processing Section
        # -----------------------------------------------------------------


        

        if (!is_uri_host_local()) {
                if (is_from_local() || allow_trusted()) {
                        route(4);
                        route(1);
                } else {
                        sl_send_reply("403", "Forbidden");
                };
                break;
        };

        if (method=="ACK") {
                route(1);
                break;
        } else if (method=="CANCEL") {
                route(1);
                break;
        } else if (method=="INVITE") {
                route(3);
                break;
        } else  if (method=="REGISTER") {
                route(2);
                break;
        };

        lookup("aliases");
        if (!is_uri_host_local()) {
                route(4);
                route(1);
                break;
        };

        if (!lookup("location")) {
                sl_send_reply("404", "User Not Found");
                break;
        };

        route(1);
}

route[1] {

        # -----------------------------------------------------------------
        # Default Message Handler
        # -----------------------------------------------------------------

        t_on_reply("1");

        if (!t_relay()) {
                if (method=="INVITE" && isflagset(6)) {
                #       force_rport();
                        unforce_rtp_proxy();
                };
                sl_reply_error();
        };

}

route[2] {

        # -----------------------------------------------------------------
        # REGISTER Message Handler
        # -----------------------------------------------------------------


        if (!search("^Contact:[ ]*\*") && nat_uac_test("19")) {
                setflag(6);
                fix_nated_register();
                force_rport();
        };

        sl_send_reply("100", "Trying");

        if (!www_authorize("","subscriber")) {
                www_challenge("","0");
                break;
        };

        if (!check_to()) {
                sl_send_reply("401", "Unauthorized");
                break;
        };

        consume_credentials();

        if (!save("location")) {
                sl_reply_error();
        };
}

route[3] {

        # -----------------------------------------------------------------
        # INVITE Message Handler
        # -----------------------------------------------------------------

        if (nat_uac_test("19")) {
                setflag(6);
                force_rport();
       

        }



        if (!allow_trusted()) {

                if (!proxy_authorize("","subscriber")) {
                        proxy_challenge("","0");
                        break;
                } else if (!check_from()) {
                        sl_send_reply("403", "Use From=ID");
                        break;
                };

                consume_credentials();
        };

        # ------    Logging calls after succesfully auth   -----------

        if (isflagset(6)) {
                xlog("L_INFO", "<%is> CH <%ct> R-URI <%ru> autenticato: NAT detected\n");
        } else {
                xlog("L_INFO", "<%is> CH <%ct> R-URI <%ru> autenticato: no NAT detected\n");
        }




       
        lookup("aliases");
        if (!is_uri_host_local()) {
                route(4);
                route(1);
                break;
        };

        if (uri=~"^sip:9999[0-9]*@") {          # International PSTN
                route(4);
                route(5);
                break;
        };

        if (!lookup("location")) {
                if (uri=~"^sip:9999[0-9]{10}@") {       # Domestic PSTN
                        route(4);
                        route(5);
                        break;
                };

                sl_send_reply("404", "User Not Found");
                break;
        };

        route(4);
        route(1);
}

route[4] {

        # -----------------------------------------------------------------
        # NAT Traversal Section
        # -----------------------------------------------------------------
        if (isflagset(6)) {
                force_rport();
                fix_nated_contact();
                force_rtp_proxy();
        }

}





route[5] {

        # -----------------------------------------------------------------
        # PSTN Handler
        # -----------------------------------------------------------------



        rewritehostport("y.y.y.y:5060");
        avp_write("i:45", "inv_timeout");

        route(1);
}

onreply_route[1] {

        if (isflagset(6) && status=~"(180)|(183)|2[0-9][0-9]") {
                if (!search("^Content-Length:[ ]*0")) {
                        force_rtp_proxy();
                };
        };

        if (nat_uac_test("19")) {
                fix_nated_contact();
                force_rport();
        };

}